Steam generator



M.` FRISCH STEAM GENERATOR E. July 9, 1940.

Filed July 17, 1935 ATTORNEY.

?atented July 9, 1940 STEAM GENERA'roa 1 Martin Frisch, Cranford, N.- J., assignr to roster Wheeler Corporation, New York, Y., a .cor-

poration of New York Application July 17, 1935, Serial No. 31,757-

' 16 Claims.

This invention relates\to steam generators. The broad general object of the invention is to provide a steam generator which incorporates the mostdesirable-features of modern practice with the various componentparts thereof so arranged that the generator may be readily adapti edto meet very small, 'very large andall intermediate steam output requirements without the necessity for individually designing and constructing a generator for each new 'requirement Somewhat more specifically, the invention provides a steam generator which may be adapted to various steam output requirements by changing customary in conventional types of generator' onlyonedimensionof'the unit, its height, with the component parts so arranged that variations in this one dimension will result in a proportional variation in the furnace volumeand the heating surface without any change in the width or length, and with the arrangement such as to require only very low head room for small units and less than the usual head room for large units than is now required by units of conventional design and comparable capacity.

Further obects of the invention are:

To provide a steam generator which occupies To simplify the supporting framework of a steam generatorso that a minimum amount will be required and to eliminate entirely the necessity for overhead structures yfor, the support of auxiliaries such as fans by arranging the various components of the generator so that lthese auxiliaries may be located, if desired, either on the operating oor-ox"` on a basement floor if provided.

ATo provide a steam generator suitable for outdoor operation and such that no building or protecting structure will be required. To provide a steam generator in which it is possible to increase the load range obtainable by arranging the furnace volume 'with respect to the unit so that low rating operation need not result in excessivecooling of the flame.

To provide a steam generator in Ywhich-super heat control may be readily effected.

To provide a steam generator in which th convection superheater is so arranged with respect to the 'other heating surface `thatzrgthere will be no direct flame impingement 'on'the super- .heater and the gases. particularly where the `unit is iiredwithpulverized coal, will m'ake an abrupt a minimum of space by reason of the elimina-change in direction of iiow before entering the superheater so that a large proportion ofthe ash with the elimination of all costly details of design and construction such as outside-water wall con\ nections which are `required by the usual conventional designs.

To provide a steam generator in which a greater portion of the heat produced in the furnace is transferred by radiation than in conventional units and in which-maximum heat absorption vin the boiler proper with a lower draft loss than is units.

To provide a steam generator which eliminates the necessity for. redesigning units for each new requirement and thereby reduce or entirely eliminate vdrawing room costs which ordinarily is a very Alarge 'item of expense.

Y To reduce the cost of field erection of steam generators by designing the unit so that a larger proportion thereof may be assembled in the shop than is now customary; a

To provide a steamA generator which delivers dry steam with the use of a minimum number vof drums, l

.through slag screens into. a superheater.

gases make a change in their direction of'flow of carried thereby will be thrown out into the fur- Which will be nace before the gases enter the superheater. 'f

' To provide a steam generator havinga furnace so arranged with respect to the boiler that every y part of the furnace volume-is effective, thus permitting whennecessary'; higher rate of heatliberation than is now customary in practice.

' To provide a steam generator which maybe constructed without any brick work, if necessary,

or if brick work is desirable, to have the amount thereof a minimum and of very simple design, l

In the preferred embodiment of the invention, ,y

these obects are attained by providing a. steam'A generator having a single pass two drum bent tube boiler disposed between and flanked by at least two water cooled combustion chambers of standard `but minimum width required for the best performance with pulverized liquid or gaseous fuel, thereby providing the boiler with at least two exposures to radiant heat. The furnaces are entirely water cooled or-may be water cooled exceptfor the ring end and the opposite end, if desired. The A,furnaces are fired from the front of the`boller and the gases iiow to the rear thereof wherefthey are causedto t'ln so that any suspended ash or dirt will be thrown out at the turn. 'I'he superheater is -disposed at the inlet end of the boilerand by virtue of this location, possesses the characteristics of both a radiant and convectionsuperheater. After passing through the superheater the gases iiow through the boiler in one pass from rear to front in a direction parallel to the boiler drums and cross all of the boiler tubes, which are arranged in staggered rows from front to rear, with theresult that heat transfer rates are obtained in a bent tube boiler which have hitherto been obtainable only in straight tube sinuous header boilers and with a much lower draft loss. because of the single pass gas -iiow through the boiler. The gases leave the boiler in the front at the center and flow to additional heat recovery apparatus such as an economizer aud/or,

as shown, an air heater which may be disposed below the boiler as shown, or at the rear or in any other desired location, and thence into an induced draft fan. 'I'he boiler tubes are staggered but are readily removableinto the furnaces andthe water wall and superheater tubes are also readily removable into the furnaces.

' The invention will be understood from the following description considered in connection with the accompanying drawing forming a part thereof and in which:

Fig. 1 is a diagrammatic view in vertical longitudinal section of steam generating apparatus embodying the invention;

Fig. 2 is a transverse vertical sectional view taken on line 2-2 of Fig. l;

Fig. 3 is a longitudinal horizontal sectional view taken online 3--3 of Fig. 1;

Fig. 4 is a partial horizontal sectional view similar to Fig. 3, showing diagrammatically another form of superheater: and

' Figi`s\adiagrammatc-sectional view on line 5-5 of Fig, 4.

Like characters of reference indicate the Vsame v or similar parts in the several views.

Referring to the drawing, the steam generator illustrated has a rectangular setting including a front wall I0, a rear walH-Land side walls I2 and I3. The generator is provided withftwopaced parallel furnaces I4 and I5 which are disposed adjacent the side walls I21 and I3 respectively of the setting. The generator is also provided with a steam generating section or boiler I6 which is disposed int'ermediate the spaced furnaces and is somewhat shorter in length than the furnaces. The furnaces and boiler are of rectangular configuration and are disposed in parallel relationship, as shown. The boiler consists of upper and .l'ower drums I1 and I8. respectively, which are connected by a plurality of bent steam generating tubes I9, arranged preferably as shown in staggered relationship in a direction transverse to the direction of flow of the gases through the boiler, which direction is parallel to the axes of the drums I1 and I8.. Tubes I9 are arranged in groups of two rows each with adjacent groups spaced in a direction longitudinally of the boiler section, suiicient distances apart to permit the tubes to be withdrawn through the lanes between tube groups into the adjacent furnaces. As shown,.th e furnaces I4 and I5 are provided with water walls and 2 I, respectively, which extend for the full length of the furnace. Thegases or products of combustion are producedin the furnace by suitable burners 22 which may burn pulverized coal, oil or gases. At their rear ends, the furnaces have outlets 23 and 24 at adjachamber 25 disposed between the furnaces and the rear end of the boiler section I6. The tubes of the furnace Water walls which extend over the outlets 23 and 24 of the furnaces are staggered as shown, to provide slag screens 26 and 21, respectively. A superheater 28 having L-shaped tubes, is disposed in the chamber 25 with the vertically extending portions of the tubes disposed adjacent the rear or inlet end of the boiler section I8 and with the horizontal portions ofthe tubes expanded into headers 29.V A second superheater having straight tubes 30 extending between headers 3| is disposed in the chamber 25 parallel to the slag screen 21. This second superheater may of course be disposed on the opposite side of the chamber 25 if desired, parallel to the slag screen 26. The two superheaters are connected in series. If desired, the superheaters 28 andl 38 may be sections of a single superheater with substantially the same result. No baiiies are utilized in the boiler section. `V'Refractory walls 32 and 38 are vertically disposed between the water walllv tubes in the furnaces I4 and I5, respectively, and

the steam generating tubes I9 and serve to sepadraft fan 4I which delivers air to the tubes of the several air heaters. After flowing through the tubes of these air heaters, the heated air flows into an air box 42 and thence into spaced, vertically disposed air boxes 43 and 44 at the front ends of the furnaces which deliver the air to the` burners 22 for both furnaces. Ash sluices 45 and 46 are provided at the bottoms of furnaces I4 and I5, respectively, and ash sluices 41 are provided at the bottom of the air heaters.

The boiler pressure parts and lcasing are suspended from girders 48 and 49, respectively, which are disposed in parallel relationship to the ax scf-thegcnerator and which are supported at their ends by"columns 50 and 5I. The girders 48 and 49 support transverse I-beams 52 and 53 which directly support the boiler drums I1 and I8 and the boiler tubes I9 through saddles 54 and 65. 'I he tubes and headers of the water walls and the casing of the boiler are supported from the main girders 48 and 49 through a plurality of hangers and56. This supporting means for the several parts of the generator eliminates the stresses due to thermal expansion and further eliminates the need of air-gas type expansion joints in the casing.

y In operation, the gases or products of combustion produced at the front ends of the furnaces, flow inl a horizontal direction through the two furnaces to the rear ends thereof in one pass through each furnace and at the rear ends of the furnaces the gases make an abrupt change in direction of iiow and pass through the slag screens 26 and 21 into the chamber 25 wherein they again cent .sides through which the gases flow into a trated. In flowing from furnace I5 into the 75 chamber 25,- the gases pass over' the superheater the result that a very high heat transfer rate is obtainable with a relatively low draft loss. The boiler has two exposures to radiant heat from the furnaces I4 and I5. Even though the boiler tubes are staggeredA in a `direction transverse to the direction of iiow of the gases through the boiler section, the boiler tubes I9 may be readilyre.

moved individually into the furnaces. Quite obviously, thewater wall tubes and the superheater tubes may also be readily removable into the furnaces. i e

With the superheaters or superheater sections disposed as described, superheat control is readily obtainable by regulating the firing in furnace I5.' With this arrangement, it is possible to obtain any desired load-superheat relationship by firing one furnace more'strongly than the other. For ex:- ample, at low loads the furnace I5 will be. fired more heavily. But regardless of the firing of the furnaces, all the gases produced-in the generator pass over all of the boiler heating surface. The slag screen 2l! providedby the proper positioning of tubes of the water wall 2 I protects superheater 30 from the slag and frame of the furnace. Slag screens 26 and 21 protect the superheater 28 disposedin the chamber 25 and also protect the boiler tubes I9. The superheaters a're drainable and by virtue of their-location, partake of the characteristics-of both radiant and convection superheaters.

` Another superheater arrangement is shown in y Figs. 4 and 5. Referring to these figures, the reranged thereacross to provide a slag screen 62.

Wall 33 is extended-toward the rear wall II to provide a gas passage 83 of about the same flow area as the Vpassage 6I.

- across the passage 63 to provide a slag screen 64.

` An L -shaped superheater section 65 has its vertically extending lportion disposed across the inlet end of the furnace, forwardly of the rear end of wall 32, anti a similar superheater section 66 has its vertically extending portion disposed forwardly of the rear end of .wall 33 and rearwardly of the forward end of wall 60. The superheater sections may be connected in series, or may be connected otherwise, or the superheater sections may be separate superheaters. With this ar rangement, superheat control is readily obtained` by varying the firing in .the two furnaces as de'- sired. The ,gases from furnace I4 pass only over the superheater S5 while the gases from furnace I5 pass over bothsuperheaters.

With this arrangement of component parts of a. steam generator, it will be perceived that a change in the vertical dimension only of the 'generator and the several component parts thereofl will result in a proportional increase in furnace volume and heating surface, in consequence' of which steam generating units may be provided for any steam output requirements Awhether large or small, by merely varying the height of the unit without changing either the width or length thereof. consequence, the

Tubes 2l are arranged same design may be utilized for all steam out-put requirements, thereby eliminating the necessity v for separately designing generators for every new use. By the use of a plurality of water cooled furnaces, it is possible to maintain the desirable ratio of water-cooled surface to the .furnace volume or to the rate of fuel firing, as the size of the generator is increased;v The arrangement is.so compact that very small units require only very low headroom and large units require proportionately greater head room but less than is required in conventional designs 'for the s'am steam output capacity.

Since all of the tubes of the generator are removable into the furnaces, there is no need for side aisles between units to provide tube withdrawal spaces. Accordingly, a series of units constructed in accordance with the invention, may

be installed side by side with a passage only at an end of the row of units or at some intermediate point Which will permit` accessto the rear of the rowv of units. However, such aisles as may be necessary tothe rear may be much narrower than in conventional arrangements because no access to any part of theunits through the sides thereof is necessary for any purpose.

Additionally; the heat recovery devices such as i air heaters and economizers as well as the fans,

may be disposed below the boiler and furnaces, and may be located either on the operating floor or on a basement oor if provided. This arrangement entirely eliminates the necessity for overhead supporting structures for these devices.

Soot blowers and any other essential equipments may be'located at the front of the units on the operating aisles and all parts of lthe boiler are accessible for repairs fromA within the` furnace. For removing the ash when pulverized coal firing is used, a simple and low cost ejector system may be installed with several openings connecting toA the furnaces and with valves which are readily controllable from the front of the boiler. Such ash as may stick to the ash receiving hoppers at the bottom of the boiler and which cannot be blown away by the soot blowers can be similarly removed. i

With the arrangement disclosed, it is apparent that the furnaces may be built inv sections by sectionalizing the headers and that they may be shop assembled and shipped as units complete with insulation and casing.

' Steam generating units -embodying theinvention are suitable for outdoor operation without anythousing means therefor since all of the component parts are included within or. below the casing of theunit. i

Although the invention has been disclosed in connection with a steam generating unit having two` furnaces disposedv in parallel relationship with each other and with` the boiler section, it will be understood that more than two furnaces may-be utilized in a unit without transcending the principles of the invention. It will also be understood that various changes may be made in thewlocationand arrangement of the several posed with respect thereto and separated therefrom by wall means, means forming a chamber connecting with the ends of the furnacesv and with the end of said section, the arrangement being such that the products of combustion flow through the furnaces, the chamber and said section in a substantially horizontal direction yand make an abrupt change in direction of flow in said chamber to separate out ash entrained in' said products of combustion, and a superheater disposed in said chamber, some of the tubes of the superheater being disposed in the path of the products of combustion flowing only from one of the furnaces to provide superheat control.

2. A steam generator comprising a steam generating section and a plurality of furnaces connecting with said section and laterally disposed with respect thereto and separated therefrom by wall means, means forming a chamber connecting with the ends of the furnaces and with the end of said section, the arrangement being such that the products of combustion flow through the furnaces, the chamber and 'said section ina substantially horizontal direction and make an abrupt change in direction of flow in said chamber to separate out ash entrained in said products of combustion, a superheater disposed in said chamber, some of the tubes of the superheater being disposed in the path of the products of combustion flowing only from one of the furnaces to provide superheat control and a slag screen for the superheater.

3. A steam generator comprising a setting', a

steam generating section and a plurality of f rality of furnaces into said section.

4. A steam generator comprising a setting, a steam generating vsection and a plurality of separate furnaces in the setting separated by wall means from the steam generating section but connected at end portions thereof with an end portion of said section, means for producing a stream of products of combustion in each furnace to flow through the furnace and said section, a superheater having tubes disposed in the path of oW ofthe products of combustion passing from one of the furnaces into said section and other tubes disposed in the'path of flow of the products of combustion passing from a plurality of furnaces, and means for varying the volume of products of combustion produced in each furnace to thereby provide super-heat control.

5. A steam generator comprising a setting, a steam generating section and a plurality of separate furnaces in the setting connecting with.

said section, a burner disposed in an end portion of each furnace to produce products of combustion therein, the arrangement being such that the products of combustiony produced in each furnace flow substantially from end to end of the` respective furnaces and thereafter i'low into and through said section, a slag screen disposed in the path of flow of the products of combustion passing from each furnace into said section, and a superheater having tubes disposed between at generating section, the arrangement being such asomar furnaceflow substantially from end to end of l the respective furnaces and thereafter flow into and through said section, a slag screen disposed in the path of .flow of the products of combustion passing from each furnace into said section and a superheater having separate tube groups disl posed between the slag, screens and the steam generating section. the arrangement being such that the products of combustion from one of the furnaces passes in heat exchange relationship with less than all of said superheater tube groups. 7. A steam generator comprising a setting, a steam generating section and a plurality of separate furnaces in the setting connecting with said section, a burner disposed in an end portion of each furnace to produce products of combustion therein, the arrangement being such that the products of combustion produced in each furnace` flow substantially from end to end of the respective furnaces and thereafter flow into 'and through said section,`a slag screen disposed in the path ofA flow of the products of combustion passing from each furnace into said section, and a superheater having separate tube-groups disposed between the slagscreens and the steam that the products of combustion from one of the furnaces passes in heat exchange relationship with all of the superheater tube groups and the products of combustion from another ofthe furnaces passes in heat exchange relationship with ,less than all of the superheater tube groups,-

whereby variations in the volume of the products of combustion produced in the respective furnaces will afford superheat control.

8. Steam generating apparatus comprising a 4.-

9. Steam generating apparatus comprising a 5.

setting,' a steam generating section in the setting. a superheater in the setting having a plurality of tube groups, means for producing a pluralityof separate streams of products of combustion for flow through said section, means causing one of said streams to flow over one of said tubo groups prior to entering said section and another ystreain to flow over a plurality of said tube groups before entering said section, and means for controlling the volume of at least one of said streams of products of combustion to thereby control the` degree of superheat obtained.

10. Steam generating apparatus comprising a setting. a steam generating section in the setting, a superheater in the setting having a plurality of tube groupS, means for producing aplurality of separate streams of products of combustion for flow through said section, and means causing one of said streams to flow. over one of said tube groups prior to entering said section and another' 75 stream to iiow over all of said tube groups prior to entering said section.

11. 'I'he method of superheating steam which comprises the steps, of passing steam through a plurality of separate super-heating zones, causing a stream of. products of combustion to-flow through one of said zones, causing a separate stream of products of combustion to flow'through a plurality of said zones, causing said streams to abruptly change their directions of flow prior to lowing through said zones, and passing said streams over slag removing surfaces prior to iiowing through said zones. K

12. A steam boiler having upper4 and lower drums, a bank of water tubes connected to said drums along the length thereof, means forming a furnace chamber laterally adjoining the space containing saidy tube bank and communicating with one end thereof, said means comprising a vertically disposed partitionl extending between and separating said furnacechamber and tube bank space except at one end thereof, means forming a second furnace chamber communicating withv the same end of the space containing said tube bank,- means for separately burning fuell in and effecting a ow of heating gases through each of said furnace chambers and then through said tube space towards the opposite end thereof, and a steam superheater 'arranged across the pathof the heating gases leaving said second furnacechamber and receiving heat mainly from said second furnace chamber.

disposed upper and lower drums, a bank of vertically disposed water tubes connected to said drums along the length thereof, means forming a main furnace chamber laterally adjoining the space containing said tube bank and communicating with the rear end thereof, said means comprising a vertically disposed partition extending between and separating said furnace chamber and tube bank space except at the krear end `thereof, means forming an auxiliary furnace chamber laterally adjoining the space containing said tube bank and communicating with the rear end thereof, means at the front end of each of said furnace chambers for burning fuel in suspension therein and effecting a flow of heating gaseslongitudinally through each of said furnace chambers and then through said tube space to- Wards the front en d thereof, and a steam superheater arranged at the rear end of said tube space andrecelving heat mainly by convection from the heating gases from said auxiliary furnace chamber.

14.lA steamboiler having upper and lower drums, a bank of water tubes Connected to said drums along the length thereof, means forming a main furnace chamber laterally adjoining the space containing said tube bank and communicating with one end thereof, means forming an auxiliary furnace chamber adjoining the opposite side of the space containing said tube bank and communicating with the' same end thereof, means for burning fuel in and effecting a flow of heating gases through each of said furnace chambers and then'through said tube space, anda steam superheater arranged to receive heat mainly from said auxiliary furnace chamber.

15. A steam boilerl having a pair of horizontally disposed upper and lower drums, a bank of vertically disposed water tubesconnected to said drums along the length thereof, means forming a vmain furnace chamber laterally adjoining the space containing said tube bank and communicating with one end thereof, means forming an auxiliary furnace chamber laterally adjoiningv the opposite side of the space containing said tube bank and communicating with the same end thereof, means at the opposite end of each of said furnace chambers for burning fuel therein Vand effecting a iiow of heating gases longitudinally through each of said furnace chambers and then through said tube space, and a steam super- 13. A steam boiler havinga pair of horizontally 'means for'ring each furnace, a chamber into which the products of combustion iiow from each furnace, steam generating surface in the setting disposed in the path of the gases which flow from said chamber, a superheater in the setting having a plurality of'tube groups, one of `said superheater tube groups being. located in heat exchange relationshipwith the products of combustion of one furnace only prior to entering said chamber, and another of said superheater tube groups being located in heat exchange relationship with the products of combustion which flow from said chamber. MARTIN FRISCH. 

